A technician often has to sketch or design ductwork and the other parts of an HVAC system. Sometimes you have to sketch the room or building you are working with. This means working with lines, angles ...

Set squares are drawing instruments used to create vertical, horizontal, and diagonal lines as well as certain angles. They may be shaped as squares, Ls, or triangles, although in American usage set ...

When you draw a shape, think about: How many sides it has. How long each side is. How many angles or corners it has. The type of angles it has - obtuse, acute or right angles. Use your ruler to ...